1. Field of the Invention
The present invention relates to an improved user demonstration for a vehicle navigation apparatus and, more particularly, to a demonstration method of reading from a disk map data pertaining to a region in which a route along which navigation is to be demonstrated is selected, and demonstrating to the user functions of the navigation apparatus while displaying the map on a display.
2. Description of the Related Art
In a navigation apparatus which performs vehicle travel guidance to enable a driver to easily drive a vehicle to a selected destination, the position of the vehicle is detected, map data for an area at the vehicle position is read out from a CD-ROM (compact disk read-only memory), and a map image is shown on a display screen while a mark representing the position of the vehicle (the user's vehicle position mark) is superposed on a predetermined portion of the map image. As the position of the vehicle changes with vehicle movement, the vehicle position mark in the image is moved or the map is scrolled while the vehicle position mark is fixed at a predetermined position, for example, at the center of the image, thereby enabling the driver to recognize at a glance the map information of the area at the vehicle position.
This kind of navigation apparatus has various functions, and a driver can use the navigation apparatus by selecting the functions to travel directly to a destination or to travel to the destination via a detour.
The navigation apparatus may have, as well as the essential function of drawing a map around the vehicle position and moving the vehicle position mark along a travel route, a guide route setting and guidance function, a map display method changing function, a travel locus display function, a map matching function, a map reading/drawing function using a point list, and a map enlargement/reduction function.
The guide route setting and guidance function sets a guide route from a starting place to a destination, displays this guide route on the map and performs intersection guidance (displaying enlarged intersection diagrams and traveling directions) to guide a driver to the destination. Guide route setting may be performed by a method in which the navigation apparatus automatically determines an optimal route from a starting place and a destination which have been input, or a method in which the user (driver) determines a route by moving the vehicle position mark along the route from a starting place to a destination by simulation. A guide route set by such a method is maintained in the navigation apparatus by storing in a memory a series of nodes (longitude, latitude) defining the route. While the vehicle is actually traveling, the series of nodes stored in the memory are searched for a guide route formed within a map display area on the screen, and the guide route thereby found is displayed so that the roads defining the route are discriminable from other roads, thereby enabling the driver to select the suitable roads and the direction of travel at each intersection.
The map display method changing function displays a map while changing map display methods so that a driver can easily view the map. A heading-up display, a north-up display, a front-wide display, a scalable display and the like may be used as map displays. The heading-up display displays a map so that the direction of travel coincides with a longitudinal direction toward the top side of the map. The north-up display displays a map so that the top of the map corresponds to the north. The front-wide display widely displays a front area in the direction of travel during the heading-up display. The scalable display displays a map on such a reduced scale that the vehicle position and a subsequent transit point or the vehicle position and a destination can be simultaneously shown in one picture, and in which the reduced scale is automatically changed according to vehicle movement.
The travel locus display function displays a route portion along which the vehicle has travelled by superposing it on the map image on the screen. In the travel locus display function, each time the user's vehicle position detected by a vehicle position detection section changes by a certain distance, the vehicle position (longitude, latitude) at the corresponding time is stored discretely as travel locus data in a travel locus memory. When a map image is shown on the screen, the data representing the travel locus to be indicated in the map image is selected from the travel locus data stored in the travel locus memory and is shown in the form of a series of white dots or the like at the corresponding position in the map image, so that the locus is discriminable. By this travel locus display function, a route along which the vehicle has travelled can be displayed as a series of dots on the roads on the screen. Therefore, for example, this function enables a driver who has driven to a strange place to return easily to his start point by reversely retracing the travel locus. Thereafter, if necessary, the driver may again trace the travel locus as a forward path to easily drive to the same place.
The map matching function corrects the vehicle position by performing map matching as desired using map information and travel locus data. In self-contained navigation (dead reckoning) which involves calculating the vehicle position by using a self-contained navigation sensor, errors can accumulate to such a degree while the vehicle travels that the vehicle position deviates from the corresponding road on the map. Therefore, map matching processing corrects the vehicle position to the corresponding position on the road by collating the travel locus with road data of the map. As the amount of error increases in self-contained navigation, the vehicle position may deviate from the corresponding road to such a large extent that map matching cannot be effected between the vehicle position and the actual present position on the road. In such a case, the vehicle position and the traveling direction for self-contained navigation are corrected by using position data (GPS data) and azimuth data (GPS azimuth) obtained from a global positioning system (GPS) installed in the vehicle. That is, the distance D between the GPS position and the self-contained navigation position is calculated and the distance D and a distance threshold value Dth previously set (e.g., 150 m) are compared. If D&gt;Dth, the vehicle position is corrected by the GPS data and the vehicle position mark is set on the road by map matching processing.
The map reading/drawing function using a point list stores the place of the user's home and other important points, designates a desired point selected from the point list and draws a map about the designated point at a time. The map enlargement/reduction function draws a detailed map, a wide-area map and the like by changing the reduced scale according to the operation of an enlargement/reduction key.
Thus, the navigation apparatus has various functions. Many people who purchase such a navigation apparatus and who are unfamiliar with it may fail to clearly understand its functions and use. Therefore, the navigation apparatus provides to the user a demonstration image for presenting the functions, and the method of using the apparatus is displayed on the display screen when the apparatus is started. Also, the demonstration image can be displayed on the display unit by selection from a menu. To change the display back to the ordinary navigation operation, a key on an operating portion of the system is operated.
Conventionally, navigation is demonstrated as described below. A demonstration region and a demonstration route are fixedly set, previously. A map containing this region is read out from a disk (CD-ROM), to be displayed on the display screen. Simultaneously, the user's vehicle mark is moved at a predetermined speed along the demonstration route (for simulation of traveling) while images for presenting the functions and the utilization method are displayed as desired by being superposed on the map.
This conventional demonstration method has the deficiency that, since the demonstration is performed by displaying a map of a fixed region, it is not easy for a driver unfamiliar with that region to understand the demonstration.
Also, since the demonstration region is fixed, the demonstration cannot be performed if the disk is changed and if the new disk has no map of the demonstration region. For example, in a case where the demonstration region is Tokyo and where a district disk having no map data of Tokyo is used in the apparatus, the demonstration cannot be performed.
Further, the demonstration may be executed repeatedly and continuously, and the disk (CD-ROM) may be accessed each time the demonstration is performed. Therefore, wear and tear on the CD-ROM drive are considerable and its life reduced.